(1) Field of the Invention
The invention pertains to disinfection apparatus for use with hemodialysis apparatus.
(2) Description of the Prior Art
One of the features of blood dialysis apparatuses--so-called hemodialysis devices--is a circulation system for dialysis fluid. This circulation system features a water supply and a dialyzer. The water supply and dialyzer are connected to one another by an initial fluid line. A second fluid line leads from the dialyzer to the discharge. The first and second fluid lines each feature a connector which connects the respective line to the dialyzer. While the dialysis fluid circulation system is being disinfected, a disinfecting apparatus is interposed into this circulation system, and the two fluid lines are connected in a bypassing manner by a shunt piece between their respective connectors.
The disinfection of hemodialysis devices is an essential cleaning step between successive dialysis processes. The goal of this disinfection is the complete cleaning and sterilization of all surfaces and devices which come into contact with the dialysis fluid and/or its concentrates or thinning fluids. Inadequate disinfection of the dialysis fluid circulation system can lead to considerable damage to the health of the patient being treated. However, the only parts of the hemodialysis device which undergo disinfection are those which can be considered part of the dialysis fluid circulation system. The reason for this is that all parts of the blood circulation system are removed and replaced by new, sterile parts after each dialysis process.
In a familiar method for cleaning hemodialysis devices, the dialysis concentrate is replaced by a disinfectant concentrate (typically from a 10-liter canister), which is pumped through the hemodialysis device. In this method, the two fluid lines (i.e., water supply line and dialysis fluid discharge line) are not shunted together. When disinfection has been completed, the disinfecting fluid remains inside the device. Before beginning the next dialysis process, the dialysis device is flushed with water. This process requires the use of a great quantity of the disinfectant. It accomplishes the cleaning of only that portion of the dialysis apparatus which is located downstream from the point at which the disinfectant is added. The applicant's hemodialysis devices A2008C-E are typical embodiments of these devices.
Improved embodiments--as represented, for example, in DE 3 447 989 and DE 3 941 103--recirculate the disinfecting solution after interposing a shunt connection between the first and second fluid lines. For one thing, this results in the complete cleaning of the dialysis fluid circulation system. It also reduces the consumption of disinfectants.
Liquid cleaning agents (e.g., formaldehyde, peracetic acid, sodium hypochlorite, or similar chemicals) are ordinarily used as disinfectants. These cleaning agents are aggressive, environmentally unsound, unhealthy, and even somewhat poisonous. It is especially necessary to exercise great caution when using mixtures of the above-mentioned cleaning agents, since an explosion or a release of elemental chlorine can occur. It has only recently been discovered that citric acid functions as a disinfectant at high temperatures. Concentrated citric acid is also aggressive and can cause dangerous reactions when mixed with other chemicals.
Aside from the high cost of transporting the disinfectant (which consists mainly of water), it is necessary to exercise great caution when replacing the concentrates for the dialysis fluid and disinfectant. To this end, special precautions have been taken to prevent the different liquids from being misrouted, i.e, to prevent these concentrates from being accidentally exchanged with one another. Examples of such precautions include special provisions for connecting the different canisters to the hemodialysis device and separate controls for the fluid lines.
There is therefore an urgent need for a disinfecting apparatus which reduces the danger of accidental exchange described above, while ensuring a safe, complete disinfection of the hemodialysis device.